For anyone that complained about no signature and no call sign, here it is.
Could you give me feedback on the new layout, please?
This is what the old layout was:
https://ibb.co/HpMdDkY
I realise now the length of wires between the loading coil the bandswitch
and the load cap is way too long for anything beyond 20m. Also the small
part of the coil was probably coupling to the aluminum case wall that is
18mm behind it, and the length of copper strap tape between the DC block
and anode cap didn't help either.
Surpsingly it worked pretty well up to 20m.
This is the new layout being worked on:
https://ibb.co/19yvVsk
The small coil is going to be separate and it will go at right angle
extending from the vacuum cap into the space between the large coil and the
blower. The anode choke has to squeeze into there as well as the HV supply,
but I think the distance should be good enough (it's difficult to put
everything near by and spaced apart at the same time). It's not quite 90
degrees away from the DC block (75 or so) that will be attached to the
anode housing at 6o'clock and it's base will be on a piece of wide copper
strap held by the vacuum cap's clamp.
The lengths of strap should be roughly: anode to suppressor - 2cm (3/4in),
suppressor is 2cm again, and suppressor to dc block 1.5cm . Then DC block
cap and between it and plate cap 2cm again. The small loading coil will go
directly there.
Coil to bandswitch 5cm (2in), bandswitch to load capacitor 5cm again.
The small coil will be made with either 10 or 12mm copper tubing (depending
on how bending will go).
Regarding the residual capacitance of the cap I can get one that is 4pF to
250pF, but it is rated at only 3kV. It is a vacuum cap with approximately
0.5mm gap between plates. Does anyone have any experience running vacuum
caps above their rated voltage? Is it possible it will Hi-pot higher?
I read conflicting info about actual voltage rating required for the plate
capacitor. ARRL handbook says (if DC is blocked) the plate cap will see
less than DC voltage when well tuned (what if it's not well tuned?). A
different website says double the plate voltage is required.
My current vacuum cap is rated at 7.5KV.
73,
Luk,SP4IT
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